When ultrapure water is used in processes for manufacturing semiconductors, the concentration of dissolved oxygen (DO) in the ultrapure water needs to be reduced such that it is, for example, equal to or less than 10 ppb, and even such that it is equal to or less than 1 ppb, by means of vacuum degasifier or membrane degasifier in order to prevent oxidization of the surface of a substrate.
In addition to ultrapure water, many kinds of chemicals are used in semiconductor manufacturing processes. In particular, isopropyl alcohol (IPA) is frequently used as a re-rinsing liquid after rinsing of a substrate and as a drying liquid used in a drying process. At present, the concentration of dissolved oxygen in IPA is not subject to any control. However, as further advances in semiconductor devices occur, in which the devices are configured with finer structures and higher integration, dissolved oxygen in IPA may cause unexpected oxidization of semiconductor devices and lower yields. Hence, the need may arise to remove the amount of dissolved oxygen in IPA to a low concentration level.
Patent Document 1 discloses a method of degassing a chemicals that contains an organic solvent. According to the method, the chemicals is fed to one side of a homogeneous polyolefin film and the other side of the homogeneous film is depressurized, whereby oxygen in the chemicals is removed.